Octyl methoxycinnamate or ethylhexyl methoxycinnamate ( INCI) or octinoxate (

USAN 280px, "Samguk Sagi" Book 04. Silla's Records. In 512, Usan-guk（于山國）was Ulleungdo（鬱陵島） Usan-guk, or the State of Usan, occupied Ulleung-do and the adjacent islands during the Korean Three Kingdoms period. According to th ...

), trade names Eusolex 2292 and Uvinul MC80, is an

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...

that is an ingredient in some

sunscreen Sunscreen, also known as sunblock or sun cream, is a photoprotective topical product for the skin that mainly absorbs, or to a much lesser extent reflects, some of the sun's ultraviolet (UV) radiation and thus helps protect against sunbur ...

s and

lip balm Lip balm or lip salve is a wax-like substance applied topically to the lips to moisturize and relieve chapped or dry lips, angular cheilitis, stomatitis, or cold sores. Lip balm often contains beeswax or carnauba wax, camphor, cetyl alcoho ...

s. It is an

ester In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ...

formed from methoxycinnamic acid and

2-ethylhexanol 2-Ethylhexanol (abbreviated 2-EH) is an organic compound with formula CHO. It is a branched, eight-carbon chiral alcohol. It is a colorless liquid that is poorly soluble in water but soluble in most organic solvents. It is produced on a large scal ...

. It is a liquid that is insoluble in water. It is primarily used in sunscreens and other cosmetics to absorb

UV-B Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...

rays from the sun, protecting the skin from damage. It is also used to reduce the appearance of scars.

Uses

Octyl methoxycinnamate is the most common active ingredient in sunscreens for protection against UV-B rays. It may be combined with

oxybenzone Oxybenzone or benzophenone-3 or BP-3 ( trade names Milestab 9, Eusolex 4360, Escalol 567, KAHSCREEN BZ-3) is an organic compound. It is a pale-yellow solid that is readily soluble in most organic solvents. Oxybenzone belongs to the class of aro ...

and titanium oxide. Studies have evaluated the efficacy of octyl methoxycinnamate in preventing postoperative peritoneal adhesions and determined that octyl methoxycinnamate covering peritoneal surfaces decreases adhesion formation. This effect is more notable when octyl methoxycinnamate is applied before the induction of trauma. Chromophore groups, such as C=C, C=O, and O-N=O, have loosely held electrons that are excited by radiation. Hence, octyl methoxycinnamate is able to absorb radiation when the electron energy level is increased to an excited state.

Spectral Information

The UV spectra of octyl methoxycinnamate contains a maximum at 310 nm.

Synthesis

Olefin metathesis has been widely studied. One of the synthesis pathways for octyl methoxycinnamate includes cross metathesis. The high efficiency of the nitro-Grela catalyst has been used in the cross metathesis of ''trans''-anethole with 2-ethylhexyl acrylate to produce octyl methoxycinnamate (86% yield).

Safety studies

One study performed in 2000 raised safety concerns about octyl methoxycinnamate by demonstrating toxicity to mouse cells at concentrations lower than typical levels in sunscreens. However, another study concluded that octyl methoxycinnamate and other sun screening agents do not penetrate the outer skin in sufficient concentration to cause any significant toxicity to the underlying human

keratinocyte Keratinocytes are the primary type of cell found in the epidermis, the outermost layer of the skin. In humans, they constitute 90% of epidermal skin cells. Basal cells in the basal layer (''stratum basale'') of the skin are sometimes referre ...

s. Estrogenic and neurological effects were noted in laboratory animals at concentrations close to those experienced by sunscreen users and were also shown

in vitro ''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called " test-tube experiments", these studies in biology a ...

. Octyl methoxycinnamate has been shown to be light sensitive with a decrease in UV absorption efficiency upon light exposure. This degradation causes formation of the Z-octyl-p-methoxycinnamate from the E-octyl-p-methoxycinnamate. In contrast, the OMC does not show degradation when kept in darkness for extended periods of time. A study carried out in 2017 by the Research Centre for Toxic Compounds in the Environment at Masaryk University, Czech Republic, indicates that octyl methoxycinnamate (EHMC) may damage human cell DNA. When exposed to sun rays, the spatial arrangement of its molecules changes and isomerisation takes place. While until now only unchanged EHMC has been researched, Massaryk University researchers focused on its isomers and found out that it has a significant genotoxic effect under lab conditions. It means that it may potentially damage human DNA and cause genome mutations which may lead to serious health risks. In swimming pools with hypochlorite in aqueous solution, octyl methoxycinnamate has been shown to produce chlorine-substituted intermediates. The chlorination intermediates of octyl methoxycinnamate demonstrated weak mutagenic effects on the Salmonella typhimurium TA 100 strain. The reactions depended on the pH, compound structures, and chlorine dose.

Ecological damage

Concern about effects on

coral reef A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of Colony (biology), colonies of coral polyp (zoology), polyps held together by calcium carbonate. Most coral reefs are built from stony corals, wh ...

s resulted in a bill in the state legislature of Hawaii to limit use of sunscreens containing octyl methoxycinnamate and

. For the same reasons, the government of

Palau Palau,, officially the Republic of Palau and historically ''Belau'', ''Palaos'' or ''Pelew'', is an island country and microstate in the western Pacific. The nation has approximately 340 islands and connects the western chain of the ...

signed a law in 2018 (becoming effective in 2020) that restricted the sale and use of sunscreen and skincare products that contain a list of ten different chemicals, including the UV filters octyl methoxycinnamate, oxybenzone and octocrylene, with fines of US$1000 for retailers who violate the law and the power to confiscate such products from non-commercial users.

Stereochemistry

Octinoxate contains a stereocenter and a double bond. It has the following stereoisomersS. Pattanaargson, T. Munhapol, P. Hirunsupachot, P. Luangthongaram (ed.): '' Photoisomerization of octyl methoxycinnamate. '' In: '' Journal of Photochemistry and Photobiology A: Chemistry '', Elsevier Verlag, vol. 161, no. 2-3, 30 January 2004, pp. 269-274.Process for producing 2-ethylhexanol
CL = DE 3530839A1
29 August 1985
EP 0216151 B1
20 August 1986. Therefore, octinoxate could consist of the following four stereoisomers:

References

{{Sunscreening agents Cinnamate esters Phenol ethers Sunscreening agents